RIPv2 Offset List

Hi,

just a minor correction to the sample solution:

It's not necessary to attach the offset-list to the Tunnel 0 interface because split horizon is still enabled from a previous task.

Cheers,

Florian

Comments

  • At the top on "Note" section, it states to load the initial configuration files for the section.... which states previous

    task should be resetted.  I agree with you if previous task is still enabled.

  • Hi,want to know why we cannot use the below offset list ( GigabitEthernet1.146 instead of Tunnel 0 ) if we want to route the traffic over VLAN 146 ?

    offset-list 1 in 3 GigabitEthernet1.13

    offset-list 1 in 3 GigabitEthernet1.146 ===>

     

    Although aware that did not get the desired result ( traffic still being routed over R1->R3 even though Gig1.146 is up as seen below)

     

    R1#sh ip int b | i 1.146

    GigabitEthernet1.146   155.1.146.1     YES NVRAM  up                    up 

    R1#traceroute 150.1.3.3 

    Type escape sequence to abort.

    Tracing the route to 150.1.3.3

    VRF info: (vrf in name/id, vrf out name/id)

      1 155.1.13.3 2 msec *  1 msec

    R1#sh ip route 150.1.3.3

    Routing entry for 150.1.3.3/32

      Known via "rip", distance 120, metric 4

      Redistributing via rip

      Last update from 155.1.13.3 on GigabitEthernet1.13, 00:00:04 ago

      Routing Descriptor Blocks:

      * 155.1.13.3, from 155.1.13.3, 00:00:04 ago, via GigabitEthernet1.13

          Route metric is 4, traffic share count is 1

  • If you set your Offset-list in from G1.146 you as you have above it would incriment the hop count of the route from that interface by 3. This would not give the desired result of chosing the VLAN 146 route above the G1.13 and tunnel 0 connection. 

    Review the task:

    Task

    • Configure an offset-list on R1 so that all traffic destined to R3's Loopback0 is routed over the VLAN 146 segment.
    • If the VLAN 146 Ethernet link is down, traffic should be rerouted over the directly connected Ethernet link to R3.

    If you apply the offsets of

    offset-list 1 in 3 GigabitEthernet1.13

    offset-list 1 in 3 GigabitEthernet1.146

    This would make the hop count for the g1.146 of 6 for the 150.1.3.3/32 route and 4 of the g1.13 link.

    Though if there were no other offset lists affecting the routes the router should choose the tunnel to forward the traffic to R3's loopback, since it should have a hop count of 2. If you did not modify it in any way.  

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